In electric machines, such as in generators for wind turbines, heat is generated when transferring mechanical energy in electrical energy and vice versa. The heat is generated in the copper conductors that form the windings of the stator by Joule losses. The generated heat has to be removed in order to avoid hotspots and insulation wearing.
The stator core and the attached windings are generally cooled by blowing air inside the stator. In axial end sections of the stator core the windings protrude and from a half loop. The protruding half loops of the windings from the end windings of the stator windings. The stator windings are cooled by blowing air through the windings, for example in an air gap between rotor and stator or through radial extending ducts of the stator core. It is also known to attach cooling pipes or hollow copper strains to the stator core in order to provide a liquid cooling. The conductor sections of the windings that are attached to the stator core are thereby cooled.
At a front face of the stator, a pressure plate for reinforcing and in particular tightening a stator lamination of the stator core is attached. Additionally, a connection for cooling fluid has to be mounted to the stator core, without affecting the tightening force of the pressure plate.
In particular, a cooling pipe for supplying cooling fluid is attached to the stator segment for transferring cooling energy to the stator windings. At the front face of the stator core, a manifold is mounted, so that the cooling fluid is supplied to or from the cooling pipe to a supply system. In conventional designs, it is complicated to combine the attachment of the pressure plate and the attachment of the manifold to the stator segment at the same time.
WO 2007/090803 A1 discloses a cooling device for an electric machine. A stator consists of a plurality of core sheets that are tightened together, so that a lamination bundle of the stator is formed. Each core sheet comprises axial channelled recesses and grooves in order to support cooling pipes and stator windings.
DE 25 15 340 A1 discloses a stator core of an electric machine in which grooves are formed for holding the windings. The stator core comprises a cooling channel.
JP 56068242 A discloses a water-cooled stator for an electric machine wherein a cooling tube made of an insulator is inserted into a cooling hole that passes through a stator core.
EP 1 168 571 A discloses a stator core with a plurality of winding slots. The windings comprise an internal conduit for circulating a coolant through the conduit.
EP 1 499 001 A1 discloses a stator core comprising an axial extending cooling channel that may be connected to an external cooling device.